The goal of this project is to investigate the neurobehavioral mechanisms of acoustic communication, particularly species-specific signal recognition as it pertains to the identification of potential mates, rivals, and predators. Because of the relative simplicity of its acoustic behavior and auditory pathways in the CNS, the cricket is an ideal model system for investigating the problems of auditory physiology that are encountered by any animal that must rely upon auditory signals for communication. These include: (1) how crickets discriminate the mating calls of their own species from those of others-and how the auditory system detects differences in the temporal pattern of mating calls; (2) how crickets (and their auditory systems) discriminates the auditory signals of crickets from those of predators, such as bats; and (3) how the auditory system is hierarchically organized to recognize species-specific signals and how this input is translated into output: adaptive behavioral acts such as phonotaxis. An important advantage of crickets for these aspects of auditory research is that questions (1) - (3) may be studied neurophysiologically and anatomically at the level of a definable network of single, identified neurons. Thus, a cellular analysis of acoustic communication can be combined with previous studies at the behavioral, genetic, and evolutionary levels of organization. The cricket auditory system is also ideal for the study of certain kinds of developmental questions. For example, how does the auditory system respond to loss of an ear? We have found that the effects of deafferentation on the auditory system can be studied in the compensatory growth responses of single, identified interneurons. The compensatory growth of dendrites restores some measure of audition. These studies may provide a convenient cellular model for studying issues of developmental plasticity such as specificity in synaptogenesis, synaptic competition, and sensory regeneration.